Effect of material interactions during thermal shock testing on IC package reliability

When large devices are molded in plastic, typically a low-stress epoxy compound is used together with a polyimide stress-relief coating. However, the interaction of these two materials, along with the die attach, is not well understood. Adverse interfacial effects on the plastic-encapsulated devices can occur with the selection of the wrong combination of materials. With increasing die size, reliability becomes an important concern. Using the optimum combination of materials should provide the longest-lived packages. However, that combination is not known at this time. This study attempts at elucidating the interaction of three main material components in a plastic package: mold compound, die attach, and die coating